1. Field of the Invention
The present invention relates to a track working machine comprising a machine frame extending in a longitudinal direction and having opposite ends, the machine frame having an upwardly recessed portion between the ends, undercarriages supporting the machine frame ends on the track for mobility thereon in an operating direction, and an operator's cab having an access below the upwardly recessed machine frame portion for permitting an operator to enter and leave the cab.
2. Description of the Prior Art
A mobile rail welding machine of this type is known from U.S. Pat. No. 4,272,664. This machine has a closed rail car body housing operator's cabs at both ends of the machine frame with access to a working area defined by an upwardly recessed machine frame portion between the machine frame ends. A vertically movable working platform forms the floor of the working area and extends in a longitudinal direction between the track rails. A flash butt welding device and a rail grind device are suspended on the upwardly recessed machine frame portion in the working area. To obtain the required free access to the rails from above, the working platform consists of a relatively narrow plank on which the operator stands during the operation.
Austrian patent No. 388,001 discloses an installation for handling assembled track sections, which comprises an elongated flat car whose loading platform serves as a working area for assembling and disassembling track sections. A crane is movable along guide rails on the machine frame for conveying ties and rails during the assembling and disassembling operation. The ties are stored on the flat car while the rails are stored on a freight car coupled to the flat car and conveyed to the working area by the crane.
U.S. Pat. No. 5,193,461 discloses a tie exchange machine with a machine frame having an upwardly recessed machine frame portion. The working tools comprising a tie exchange device and a tamping unit are housed in a working area below this machine frame portion. A crane with an adjustable boom runs atop the machine frame for conveying old ties away and new ties to the working area. The machine frame has an opening providing access to the working area for the ties being conveyed.